What is Red Giant Star? Red Giant Star Definition and Important Facts
The majority of stars in the cosmos are main sequence stars, which undergo nuclear fusion to transform hydrogen into helium in their cores.
However, once core fusion stops, gravity takes over and starts to compress the star. This increases the star's internal temperature and ignites a shell of hydrogen burning around the inert core.
The star then becomes a "Red Giant" as a result of its enormous expansion and brightness increase.
Red Giant Star Size and Diameter
Red giant stars bloat to a diameter of 62 million to 620 million miles (100 million to 1 billion kilometers), which is 100 to 1,000 times wider than the current size of our sun.
Red Giant Star Temperature
These stars' energy is dispersed over such a large area, their surface temperatures are relatively cool, only rising to 4,000 to 5,800 degrees Fahrenheit (2,200 to 3,200 degrees Celsius).
The temperature of the Red Giant Star - The Red Giant Star is little over half as hot as the sun.
The core temperatures of red giants eventually approach the level where helium fuses to form carbon.
(This is the "triple alpha process" since it involves three helium-4 isotopes or alpha particles.)
Why is a red giant so named?
This temperature change causes stars to shine in the redder part of the spectrum, giving rise to the name "Red Giant," but they're often more orangish in appearance.
Red giants are so named because of their large size and the appearance of red color.
Red Giant Star Facts:
Helium-to-carbon ignition is a relatively gradual process if the star is at least 2.2 times more massive than our sun. But it happens with an explosive flash for stars that are less massive.
The end of a star's red giant phase is generally the most violent period of its life. The material from the bloated, dying star's outer layers throws out in Intense episodic bursts.
After about 6 billion years from now, our Sun will run out of fuel in its core when it enters the red giant phase.
Our own sun will change into a white dwarf after spending around 1 billion years as a red giant, packing most of its initial mass into a sphere roughly the size of Earth.